Chain construction



' Dec, 2, 19 47. J MccANN 2,431,764

CHAIN CONSTRUCTION Filed June 21, 1944 Hal. F152.

H /5 /6 M /5 /6 John F. Mc Cazm INVENTOR.

BY M

ATTORNEY.

Patented Dec. 2, 1947 CHAIN" CONSTRUCTION John F. McCann, Longmeadow, Mass, assignmto Chain Belt Company, Milwaukee, Wis., a corporation of. Wisconsin Application June. 21', 1944, serial No. 5.41529; 13 Claims. (or. Sll-Sl- This invention relates to chain construction.

The invention has been applied particularly to the construction of small sprocket chains such as roller chains in which the side plates are press fitted onto the bushings. The invention maybe applied, however, to various other types of chains.

In the press fitting of side plates onto tubular bushings the standard practice has been to make the hole in the side plate a few thousandths of an inch less in. diameter than the outside of the bushing and, after the separate parts are hardened, to press the side plate onto the end of the bushing. This practice has a tendency to reduce. the internal diameter of the bushing at the ends and to cause undesirable wear of the bushing and pins at this location. Furthermore, such chain has only a limited ability to withstand side pressures as in the case of sprocket misalignment and when used for high speed operations the vibration of the chain produces a tendency for the side plates of the bushing links to spring outwardly and lock with the side plates oi adjacent pin links.

Various attempts have been made to overcome these difficultiesas by providing external grooves adjacent the ends of the bushing into which the side plates are pressed. Grooves of various: shapes have been proposed, one shape proposed being a tapered groove to correspond with thepitch of the punched hole in the side plate which naturally results from the breakout of the metal in the punching operation. Such a construction decreases the press fit between the side plate and bushing and does not provide as strong a grip between the parts, thereby tendingto allow the bushing to turn in the side plates. The close tolerances required are difficult to maintain. Only a slight improvement is obtained against lateral displacement of' the side plates.

Another method of correcting the difii'culties has been to provide projections on the outer sur face of the bushing by hatching the surface of the bushing at spaced intervals around its cir-' cumferential adjacent the end. The. projections out into the side plate and are supposed to hold it against displacement as well as to hold the bushing against turning. This construction gives about the same results as the chain with grooved bushing.

Both of these methods are costly;

One of the objects of' the present invention is to provide a stronger lock of the side plate upon the bushing to prevent displacement of theside plate by sprocket misalignment.

Another object is to prevent undue wear of the bushing at its ends by the pin.

Another object is to provide a chain in which the pin can be readily oiled from the outside.

Another object is to provide a simple and less costly method of interlocking the bushing with the side plates.

The invention is illustrated in the accompanying; drawing with certain dimensional features exaggerated to more adequately show the sameand in which:

Figure I is a side elevation of a bushing blank with one side broken away and sectioned;

Fig. 2 is a diagrammatic section showing the forming of the bushing to expand its ends;-

Fig. 3 is a side elevation of a formed bushing: with one side broken away and sectioned;

Fig. 4 is a side elevation of a side plate;

Fig. 5 is an axial section through a pair of bushings with aside plate in position for assemlvz Fig. 6 is a similar section of the bushings and side plateafter assembly; and

Fig. '1 is a plan view of a completed chain with a bushing link sectioned to show the construction.

The present invention utilizes a simple form of interlock with better press fit than heretofore employed. The expensive grooving and notching operations are avoided and only a single step is added to the'manufacturing operationsin the making of the chain.

In carrying out the invention a cylindrical bushing l, which is illustrated as a curled bush inghaving a longitudinal seam, is first ground to size, and while soft it is expanded at each end to flare the same outwardly. The flaring operaticn may be carried out cold by any suitable forming machine. For example, the bushing may-be stood on end and gripped by two complementary laterally movable die. members 2' and 3 having the die. shape of the externally flared bushing; Punches 4 and.5 are. then simultaneously inserted from opposite ends in the manner illustrated in Fig. 2 to flare the ends of the bushing outwardly into the tapered recesses in the ends of the die members 2 and 3'.

The resulting bushing illustrated in Fig; 3'has a cylindrical body 6 and flared or outwardlytapered end portions 1. The hole 8- in side plate 9, due to breaking-or tearing of the metal in the, punching operation, has a pitch or tapen When the side-plate 9- is pressed onto the bushings l and Ill, the corresponding ends of the latten ar forced inwardly and are gripped by the side plate as shown in Fig. 6. The gripping force is increased by reason of the contour of the ends of the bushing and the differential in the dimensions of the ends of the bushings and of the side plate holes. With the bushing illustrated in the drawing, the contraction of the ends, however, does not eliminate the inside flare in diameter of the bushing. This flare provides an end space I I between the bushing and its pin l2 which facilitates oiling of the pin and tends to avoid end wear of the bushings, and constitutes subject matter disclosed and claimed in my copending application Serial No. 630.894, filed November 26, 1945, and entitled Chain bushing and side plate construction.

By making the size of the bushing body relative to the diameter of the hole in the side plate smaller than that heretofore employed in a bushing of constant diameter throughout its length, possible upsetting of the metal of the bushing under the press fit is avoided. The same result may be accomplished by enlarging the size of the opening in the side plate for a given size bushing provided the flare is adequate.

Various combinatons of dimensions may be employed and various sizes of chain may be made embodying the invention. The construction of the invention provides a substantially greater gripping force between the side plates and the bushings by the simple operation of flaring the ends of the bushing to produce a greater dimensional difference between the bushing and the opening in the side plate. The dimension difference between the body of the bushing and the opening in the side plate is reduced to avoid the possibility of undesirable upsetting of the metal of the bushing when the side plate is press fitted thereon.

In carrying out the method of the invention only a single step is added to the chain manufacture, i. e. the step of flaring the ends after sizing the bushing and while the latter is still soft. The dies for this operation are simple and inexpensive and are not subject to critical wear.

. After flaring the ends of the bushing the latter is generally case hardened as by carburizing, tumbled to remove the carburizing scale and then assembled with the side plates in the ordinary manner of chain assembly. In this assembly operation two bushings are first pressed endwise into the corresponding openings in a side plate and then the same are pressed in the opposite endW-ise direction into the corresponding openings in a second side plate. For roller chain, rollers 13 should be placed upon the bushings prior to assembly of the same with the second side plate.

The final chain, as illustrated in Fig. 7, is composed of a plurality of bushing links M each having a pair of side plates 9 secured together by "a pair of bushings I, and the bushing links i i are joined end to end by pin links l5, each of which has a pair of side plates l6 secured together by pins I2 which pass through the opposite bushings l of two adjacent bushings links l4.

By reason of the construction. described the pins 52 have a bearing engagement with the respective'bushings I principally in the body portions 5, the ends of the bushings being flared- Tests with chains constructed in accordance with the invention have shown that they have over fifty-per cent greater resistance to lateral displacement of the side plates under static load than regular press fit roller chains and over forty per cent greater resistance to such displacement than locked press fit chain heretofore employed as described above. This makes it possible to utilize the chain of the present invention in higher speed operations and under conditions of greater tolerance with respect to sprocket alignment and the like, as encountered in motor cycle drives.

Various embodiments of the invention may be employed within the scope of the accompanying claims.

I claim:

1. In a chain link, a bushing, and a pair of side plates with the ends of the bushing press fitted into holes in said side plates to form a journal for the pin of an adjacent link, said bushing being substantially cylindrical with its end portions tapered outwardly, the diameter of the cylindrical portion of the bushing being slightly in excess of the diameter of the side plate holes, and the external surface of the bushing being free from grooves and shoulders at its ends.

2. In a chain of the class described, a tubular bushing, and a side plate press fitted on to each end thereof with a substantial press fit interference, said tubular bushing being initially flared at the ends to provide the major portion of the press fit interference and being substantially free from grooves and shoulders at its ends.

3. In a chain of the class described having side plates press fitted on to the ends of bushings, a cylindrical bush'ing'having its ends flared outwardly to enlarge the diameter thereof as compared to the diameter of the cylindrical body portion of the bushing and increase the grip of the side plates resulting from the press fit, thereby preventing lateral displacement of the side plates from the bushings.

4. In a chain of the class described having side plates press fitted on to the ends of bushings, a cylindrical bushing having its end flared outwardly to enlarge the diameter thereof as compared to the diameter of the cylindrical body portion of the bushing and increase the grip of the side plates resulting from the press fit, thereby preventing lateral displacement of the side plates from the bushing, the shape of the outer surface of the enlarged ends of the bushing interlocking the same with the side plates to prevent rotation of the bushing in the side plates.

5. In the manufacture of chain of the class described, the method of increasing the grip of the side plates upon the ends of the bushings to prevent lateral displacement of the side plates in service, comprising enlarging the ends of the bushings to provide a substantial press fit tightness at the extreme ends thereof without the formation of grooves and shoulders tending to loosen the side plates in service.

' 6. In the manufacture of chain of the class de scribed, the method of increasing the grip of the side plates upon the ends of the bushings to pre-- vent lateral displacement of the side "plates in service, ccmprising providing a cylindrical bushing'having an outside diameter greater than the diameter of the opening in the side plate to be '7. In the manufacture of chain of the class described, the steps of flaring the ends of a cylindrical tubular bushing outwardly, and thereafter press fitting a side plate on each end thereof.

8. In the manufacture of chain of the class described, the steps of flaring the ends of a cylindrical tubular bushing outwardly, hardening the bushing to increase its wear resistance and m ke it more resistant to deformation, and thereafter press fitting side plate on each end thereof.

9. The method of manufacturing a bushing link of a chain, comprising forming a pair of cylindrical tubular bushing blanks, enlarging the ends of the blanks to provide flared ends therefor, hardening the bushings to increase the wear resistance thereof and the resistance to deformation, forming a air of side plates with openings punched through their respective ends for receiving corresponding ends of the bushings, said punching operations tapering the openings with a minimum diameter less than the outside diameter of the bushing blanks, and press fitting the side plates upon the corresponding ends of the bushings with the sides of the respective plates having the minimum diameter of the openings disposed towards the inside of the link.

10. In the manufacture of chain of the class described. the forming of a bushing adapted to be press fitted into openings in side plates, comprising positioning a tubular cylindrical bushing blank of substantially uniform thickness in a confining die having a flared recess surrounding at least one end of the blank and leaving said end free for access thereto, applying a tapered punch to said free blank end to flare the same outwardly into the die recess, and similarly forming the opposite end of the blank.

11. In the manufacture of chain of the class described, the forming of a bushing adapted to be press fitted into openings in side plates, comprising positioning a, tubular cylindrical bushing blank of substantially uniform thickness in a confining die having a flared recess surrounding each end of the blank and leaving the ends free for access thereto, and simultaneously forcing a tapered punch into each end of the blank to flare the same outwardly into the corresponding die recess.

12. In a chain of the class described, a tubular bushing, and a side plate press fitted on to each end thereof with a press fit interference substantially in excess of that customarily employed with cylindrical bushings of the same size, said tubular bushing being initially flared at the ends to provide the excess press fit interference and to further rovide in the completed chain a space between the bushing and pin at each end of the bushing avoiding concentration of Wear on the bushing at this location.

13. In a chain of the class described having side plates press fitted on to the ends of the bushings, a cylindrical bushing having its ends flared outwardly to enlarge the same and increase the grip of the side plates resulting from the press fit, thereby preventing lateral displacement of the side plates therefrom, said flared ends providing in the completed chain a tapered enlargement of the internal diameter of the bushing at the ends to avoid concentration of wear of the bushing in the region of the side plates and facilitate oiling.

JOHN F. McCANN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,024,183 Pribil Dec. 17, 1935 2,155,626 Weiss Apr. 25, 1939 1,466,953 Loomis Sept. 4, 1923 2,155,584 Bryant et a1 Apr. 25, 1939 2,129,407 Dalrymple Sept. 6, 1938 

